Respirators are commonly worn over the breathing passages of a person for at least one of two common purposes: (1) to prevent impurities or contaminants from entering the wearer's breathing track; and (2) to protect other persons or things from being exposed to pathogens and other contaminants exhaled by the wearer. In the first situation, the respirator is worn in an environment where the air contains particles that are harmful to the wearer, for example, in an auto body shop. In the second situation, the respirator is worn in an environment where there is risk of contamination to other persons or things, for example, in an operating room or clean room.
Some respirators are categorized as being “filtering face-pieces” because the mask body itself functions as the filtering mechanism. Unlike respirators that use rubber or elastomeric mask bodies in conjunction with attachable filter cartridges (see, e.g., U.S. Pat. No. 5,062,421 to Burns et al.) or insert-molded filter elements (see, e.g., U.S. Pat. No. 4,790,306 to Braun), filtering face-piece respirators have the filter media comprise much of the whole mask body so that there is no need for installing or replacing a filter cartridge. As such, filtering face-piece respirators are relatively light in weight and easy to use.
Various embodiments for securing the respirator to the user are known in the art. A known embodiment includes the use of buckles, secured to the respirator, with a strap that is removably secured to each of the buckles and that passes behind the user's head relative to the respirator mask. The strap may be tightened and loosened by operation of the buckle. In various known embodiments, the buckle has a slot, with a single-piece cinch bar splitting the slot into two parts. A user may secure the strap to the buckle by passing the strap through one part of the slot in one direction, and then passing the strap through the other part of the slot in the opposite direction such that the strap is held in place through friction, such as friction between the two ends of the strap.